β-NaYF_4:Yb,Er复合丝素荧光薄膜的制备与表征

Preparation and characterization of β-NaYF_4:Yb,Er composite fluorescence silk fibroin film

采用高温热分解法合成β-NaYF_4:Yb,Er纳米晶体,然后将丝素薄膜作为柔性基底材料与β-NaYF_4:Yb,Er复合制备了一种丝素基荧光薄膜。使用透射电镜(TEM)、高分辨透射电镜(HRTEM)、X-射线衍射仪(XRD)、傅立叶红外光谱仪(FT-IR)、紫外可见分光光度计、荧光光谱仪对β-NaYF_4:Yb,Er和丝素基荧光薄膜进行表征。结果表明:β-NaYF_4:Yb,Er纳米晶体平均粒径35 nm,分散性良好,六方相,表面包覆油酸。β-NaYF_4:Yb,Er纳米晶体质量浓度对丝素基荧光薄膜的透光率有重要影响,随β-NaYF_4:Yb,Er质量浓度的提高,丝素基荧光薄膜的透光率不断减小。丝素基荧光薄膜在980 nm激光器激发下荧光光谱图中有3个发射峰,分别对应于Er3+离子~2H_(11/2)→~4I_(15/2)(520 nm)、~4S_(3/2)→~4I_(15/2)(540 nm)、~4F_(9/2)→~4I_(15/2)(660 nm)能级跃迁,其主要的发光机制是能量传递上转换。

β-NaYF,：Yb,Er nanocrystals were firstly prepared by thermal decomposition and then spin-coated on silk fibroin film substrate to obtain fluorescence silk fibroin film. β-NaYF4：Yb, Er nanocrystals and fluorescence silk fibroin film were characterized by transmission electron microscopy （TEM）, high resolu- tion transmission electron microscopy （HRTEM）, X-ray diffraction （XRD）, Fourier transform infrared spectrosco- py （FT-IR）, fluorescence spectra and optical transmittance spectra. It could be seen that the as-prepared β-NaYF4：Yb, Er nanocrystals with the average size of 35 nm were well dispersed, hexagonal-phase and coat- ed with oleic acid. The concentration of β-NaYF,：Yb, Er nanocrystals had a major impact on transmittance of fluorescence silk fibroin film. The transmittance decreased with concentration increasing of β-NaYF4：Yb,Er nanocrystals. The UC emission spectrum of fluorescence silk fibroin film under 980 nm laser excitation showed three emissions located around 520, 540 and 660 nm, which arose from the 4f configuration transi- tions of Er＋ from 2H_（11/2）→4I_（15/2）（520 nm）、4S_（3/2）→4I_（15/2）（540 nm）、4F_（9/2）→4I_（15/2）（660 nm）, respectively. The main upconversion luminescence mechanism was energy transfer upconversion （ETU）.